Adjust it as required. For precise measurements, select the segment, open the Frame Border Editor, and type in a width and height under the General tab.

Duplicate your segment by selecting it, then typing Ctrl-D (Windows) or Cmd-D (Mac). An exact copy of the segment will appear, which you can move into position.Note that you don’t need to make all the segments the same size, and that they may overlap if you want to rebuild the project after printing into a multi-level mosaic.

In the Pages hover, add a new page.

Reset the size of the page to printer-friendly dimensions.
To reset the page size, double-click in the grey area around the canvas. This will open the Canvas Settings Editor where you can custom-set your page size.

On the new blank page, right-mouse-select again to choose Insert > Reference Regions.
You will now find a Destinations option, with a reference to the page(s) containing your page segments.
Choose one of the page segments to apply it to your page.

The segment will be applied at 100% size. It can be resized if required.

Continue to add as many pages as required to rebuild your project into segments.
Note that you can add more than one segment to a page.

Last, exclude the original full-sized composition from output.

On the Pages hover, right-mouse select the page, and choose to Exclude from output.

You can now render or print your project – only the pages with segments will be rendered.